Design of damping properties of hybrid laminates through a global optimisation strategy

In this paper a global optimisation technique for the design of damping properties of hybrid elastomer/composite laminates is presented. The goal of the procedure is to maximise the first N modal loss factors of the laminate subject to constraints on the in-plane and out-of-plane stiffness along with a constraint on the weight of the plate. The problem is considered in the most general case: no simplifying hypotheses are made on the behaviour of the hybrid laminate, thus allowing us to consider as design variables the number of layers (both of the elastic and viscoelastic layers), their thickness and orientations as well as the position of the viscoelastic plies within the stacking sequence. The proposed approach relies on one hand, upon the dynamic response of the structure in terms of natural undamped frequencies and modal loss factors which are evaluated using the well-known Iterative Modal Strain Energy (IMSE) method, and on the other hand on the use of genetic algorithms as optimisation tool to perform the solution’s search. As an example, the method is applied to a rectangular plate and the results demonstrate the effectiveness of the proposed strategy.